240, HIROSHI OHSHIMA 
is now open throughout, both at the mouth and anus, the lumen 
becoming quite spacious. 
19. During the transformation of the pentactula into the ten- 
tentacled young, the pore-canal becomes obliterated. Of the 
secondary tentacles those given out dorsad from the paired 
ventral radial canals appear first, while those given out ventrad 
from the same canals are completed: very late. Among the 
respective pair the right one appears slightly earlier than the left. 
20. In the young, the branches of the tentacle can be classified 
in three orders, and are sent out either in dextrorse or sinistrorse 
spiral according to a definite arrangement. The angular diver- 
gence of branches is about one-quarter or two-sevenths. The 
ventral pair remain for a long while in a twice dichotomously 
branched condition, and further branching usually takes place 
very late. 
21. The increase of pedicels takes place faster in the mid- 
ventral radius than in the others, while those of the dorsal 
radii increase slowly. In none of the stages is any asymmetrical 
feature found as concerns the numbers of pedicels between 
right and left. ) 
22. Along the mid-ventral radius I could ascertain that the 
pedicels up to the twelfth appear according to an almost definite 
order. But pedicels above the fourth may undergo some varia- 
tions with respect to the order of appearance or the position 
on the right and left. 
IMPERIAL COLLEGE OF SCIENCE AND TECHNOLOGY, LONDON. 
February 11, 1920. 
17. BIBLIOGRAPHY. 
1. Ackermann, August (1902).—‘‘ Uber die Anatomie und Zwittrigkeit 
der Cucumaria laevigata”, ‘Z. w. Z.’, Bd. lxxii, 1902. 
2. Arts, Louis des (1910).—‘‘ Uber die ersten Entwicklungsstadien von 
Cucumaria frondosa unter Beriicksichtigung anormaler 
Verhiltnisse ’’, ‘ Bergens Mus. Aarb.’, 1910, no. 13. 
3. Becher, Siegfried (1908).—‘*‘ Die Stammesgeschichte der Seewalzen ’’, 
‘Ergebn. u. Fortschr. Zool.’, Bd. i, Heft 3, 1908. 
